Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

902
FXUS63 KLOT 180820
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
220 AM CST Sun Jan 18 2026

.KEY MESSAGES...

- Accumulating snow is expected late this afternoon into this
  evening, with slippery travel conditions expected.

- A strong arctic cold front will move across the area late this
  evening with west/northwest winds gusting to 40 mph. Some
  blowing snow will be possible.

- Bitterly cold conditions are expected late tonight through
  Tuesday morning with wind chills 15 below to 25 below zero
  expected Monday morning.

- A clipper system may bring accumulating snow to parts of the
  area Tuesday night into Wednesday morning.

&&

.DISCUSSION...
Issued at 220 AM CST Sun Jan 18 2026

A strong arctic cold front will move across the area late this
evening into the early overnight hours. Ahead of this front, a
period of snow is expected to spread across the area starting in
the late afternoon and continuing through mid/late evening, with
the focus for snow along and north of a LaSalle to Rensselaer
line. Unlike the system Saturday evening that was expected and
did weaken as it moved across the area, this system will likely
continue producing snow as moves across the entire area and with
the dry/cold airmass in place, fluffy dry snow may result in an
inch of snow accumulation, perhaps 1-2 inches across parts of
northeast IL. The accumulating snow looks to end as the cold
front arrives but there may still be a period of flurries or
snow showers into the early overnight hours.

Winds behind the cold front will quickly increase into the 20-30
mph range with gusts 35-40 mph possible. Its unclear how much
blowing snow may occur with the expectation that most, if not
all the falling snow will be over. More likely is low drifting
snow, presenting issues for north/south roads in open areas.
Opted not to include any blowing snow in the forecast/grids, but
this will need to be looked at again with later forecasts.

High temps today may struggle to reach 20, hold steady for a few
hours during the snow, then steadily fall behind the front with
low temps by daybreak Monday morning around zero or a few
degrees below zero across the northwest cwa, to the low single
digits for the rest of the area. With winds still expected to be
in the 20-25 mph range, with higher gusts, this will allow wind
chills in the 20 below to 25 below range for most of our IL
counties. Wind chills for Chicago and along/east of I-57 may be
more in the 15 below to 20 below zero range. Opted to draw the
boundary for the cold weather advisory along the IL/IN state
line, though as noted, marginal criteria on the far eastern
edge of the advisory. High temps Monday only rebound into the
mid/upper single digits for most areas, perhaps some low teens
across central IL. Wind chills are expected to remain below zero
all day Monday, Monday night and into Tuesday morning. Similar
low temps are expected again Tuesday morning, but with lower
wind speeds, wind chills look to be in the 10 below to 15 below
range.

One change to the forecast that will need to be watched is
another weak wave that moves across the region late Monday
afternoon into Monday evening. Models are dry with this feature,
as is the blended guidance, but if this materializes in the very
cold airmass, there may at least be some flurries.

Models remain in overall good agreement with a clipper system
for Tuesday night into early Wednesday morning with a chance for
accumulating snow across at least far northern IL. Still a few
days away and snow location/amounts will be dependent on the
exact track, but overall, this has been a well handled feature
among the models for several days. Another feature of note is a
cold front late Wednesday or Wednesday night, that may bring
another period of flurries or snow showers.

Temps still look to briefly moderate Wednesday, ahead of the
clipper system when highs may reach the upper 20s/lower 30s.

There remains quite a bit of uncertainty for the end of the
week into the weekend with the potential for an active pattern
for or near the local area. The ensembles seem to be in a
little better agreement for precipitation chances for the local
area, but there is still a decent spread in possibilities.
Regardless of whether precip develops for the local area,
current trends continue to favor a cold/very cold pattern. cms

&&

.AVIATION /06Z TAFS THROUGH 12Z MONDAY/...
Issued at 1115 PM CST Sat Jan 17 2026

Key Messages:

- Another round of snow with IFR/MVFR visibilities is expected
  late Sunday afternoon and evening.

- Periods of MVFR ceilings are expected during the current TAF
  period.

- Winds will turn west-northwesterly and gust to around 30-35
  kts behind an arctic cold front tomorrow night.


Saturday evening`s snow will continue to taper off at the
Chicago metro terminals through 06-07Z. However, flurries may
persist through the overnight hours while MVFR/low-end VFR
stratus remains overhead.

While the lower clouds should largely clear out by mid-morning,
another clipper-type weather system will dive into the region
during the afternoon, bringing another period of snow with
IFR/MVFR visibilities and MVFR ceilings. Another 0.5-1.5" of
dry/fluffy snow accumulation is expected with this round, with
a lower-end chance for a localized 2" somewhere as well. This
next round of steadier snowfall should largely conclude prior
to midnight tomorrow night, but again, flurries or even a few
additional brief snow showers may occur Sunday night/early
Monday morning after the main wave of snow has ended.

Sustained westerly to southwesterly winds primarily between 10
and 15 kts with gusts closer to 20 kts are expected through
Sunday evening. Winds will then shift more west-northwesterly
during the late evening behind an arctic cold front. Gusts near
and in excess of 30 kt are likely to be observed for several
hours after the frontal passage.

Ogorek

&&

.MARINE...
Issued at 220 AM CST Sun Jan 18 2026

The gale watch has been upgraded to a gale warning for tonight
into Monday morning for all of the IL and IN nearshore waters.

A heavy freezing spray warning has been issued for the
nearshore waters east of Gary, IN.

A strong arctic cold front will move across the area tonight,
bringing a period of gale force winds between 35 and 40 knots.
These strong winds will slowly diminish on Monday with gales
ending across the IL nearshore Monday morning and then across
the IN nearshore Monday afternoon. Very cold temperatures will
spread across the area behind this cold front and combined with
the high waves, heavy freezing spray is expected across parts of
the IN nearshore waters, mainly east of Gary, IN. cms

&&

.HYDROLOGY...
Issued at 253 PM CST Fri Jan 16 2026

The upcoming extended period of very cold temperatures will likely
result in the rapid development of ice on area rivers and streams
which may increase the chance of localized ice jam flooding. Last
week`s heavy rainfall has resulted in increased streamflow in
several basins, including the Fox, Des Plains, and Illinois River
basins. This higher streamflow will result in a greater potential
for freeze up ice jam flooding.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Cold Weather Advisory from 3 AM to 10 AM CST Monday for ILZ003-
     ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-
     ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-
     ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

IN...None.
LM...Small Craft Advisory until 3 AM CST early this morning for the
     IL and IN nearshore waters.

     Gale Warning from midnight tonight to 9 AM CST Monday for
     Winthrop Harbor IL to Gary IN.

     Gale Warning from midnight tonight to 3 PM CST Monday for Gary
     to Burns Harbor IN-Burns Harbor to Michigan City IN.

     Heavy Freezing Spray Warning from midnight tonight to 3 PM CST
     Monday for Gary to Burns Harbor IN-Burns Harbor to
     Michigan City IN.

&&

$$

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